Heavy Ladybeetle Poulations

Images of insects swarming upon a residential neighborhood is the stuff science fiction movies are made of.

But fiction has become reality for many residents who are invaded year after year by the multicolored Asian ladybeetle. And Ohio State University entomologists are predicting this year's ladybeetle infestations to be severe.

"Residents tell us that it just keeps getting worse and worse every year," said Joe Kovach, of Ohio State's Integrated Pest Management program. "And we think numbers will be much higher this year."

The reason, said Kovach, is a new food source – the soybean aphid. The aphid, first discovered in Ohio last year, was found in abundant numbers throughout soybean fields, especially in the north and northeast, providing an ample food source for the ladybeetles.

"In fields throughout the north and northeast we were finding thousands of soybean aphids per plant. It just makes sense that the more aphids you find the more ladybeetles are present," said Ohio State entomologist Ron Hammond. "But I have never seen those kinds of ladybeetle numbers in soybean fields in my entire life. The beetles were quite happy this year."

Which is unfortunate for Ohio residents who must contend with large ladybeetle populations that will soon be taking flight to seek an over-wintering site. "The food quality is going down," said Kovach. "The ladybeetles will start moving after the first frost and the warm days that follow." Kovach said the first frost is weather dependent and ranges anywhere between now and Oct. 25 depending on what area of the state one lives in.

The multicolored Asian ladybeetle, native to Asia and introduced to the U.S., is considered a beneficial insect because it feeds on other pests such as aphids and mites. But the insect is a nuisance for homeowners, since it tends to congregate in homes in large numbers, and getting rid of them has become quite a challenge.

"Prevention is the key," said Kovach. "Finding ways to keep ladybeetles out of the home is the first step to controlling them."

There are steps homeowners can take to help keep ladybeetle numbers in check.

Caulking spaces around the outside of the house that would provide a crawl space for ladybeetles to enter, including where vinyl siding meets window sills and where the roof line meets the sides of the house.

Kovach also recommends homeowners apply foam sealant to any openings in interior walls of rooms with southern or western exposure. Foam sealant should be applied behind trim around windows, light fixtures, bathroom and kitchen pipes and behind baseboards to reduce the beetles' access to these rooms.

Applying insecticides around windows, eaves and doors and other spaces on the outside of the house. Kovach said insecticides should be applied before the first warm day after the first frost.

Cleaning up dead ladybeetles in and around the home. Ohio State researchers speculate that dead ladybeetles release chemicals that attract other ladybeetles to that location.